This invention relates in general to a fluid, gas and/or vacuum flow system, and to a method for the fabrication and/or formation of same. More particularly, the invention relates to a method for the fabrication of a bi-directional flow system suitable for use in the delivery of ink in an ink jet printer, for example, and to such a system having a laminate gasket manifold with a plurality of fluid-flow channels therein.
Without limiting the scope of the invention, its background is described in connection with ink jet printers, as an example. It should be understood that the solutions provided herein in connection with an ink flow system for use in an ink jet printer may have use in other applications, such as where vacuum is required.
Modern color printing relies heavily on ink jet printing techniques. The term xe2x80x9cink jetxe2x80x9d as utilized herein is intended to include all drop-on-demand or continuous ink jet printer systems including, but not limited to, thermal ink jet, piezoelectric, and continuous, which are well known in the printing industry. An ink jet printer produces images on a receiver medium (such as paper) by ejecting ink droplets onto a receiver medium, such as paper, in an image-wise fashion. The advantages of non-impact, low-noise, low-energy use, and low cost operations, in addition to the capability of the printer to print on plain paper, are largely responsible for the wide acceptance of ink jet printers in the marketplace.
The print head is the device that is most commonly used to direct the ink droplets onto the receiver medium. A print head typically includes an ink reservoir and channels which carry the ink from the reservoir to one or more nozzles. Typically, sophisticated print head systems utilize multiple nozzles for applications such as four-color ink jet and high speed continuous ink jet printer systems, as examples. In order to fabricate a four-color ink jet print head that consists of one monolithic silicon die with one or more arrays of nozzles for each color, an ink manifold is often used in the fluid delivery system.
Ink manifolds are typically formed of a number of laminate sub-layers stacked on top of each other to form a sub-assembly having internal fluid flow channels. Various lamination techniques are known including stamping, laser machining, or chemical etching, to produce the channels in sheets of steel or plastics which are then adhesively bonded together to form the manifold sub-assembly. A known problem with these prior art lamination methods occurs with the use of liquid adhesives or epoxies. Such adhesives can spill into the channels during stamping or machining resulting in a clogged channel and poor performance of the fluid flow system. Oftentimes, the fabrication process is followed by a cleaning of the manifold sub-assembly which increases the overall costs of manufacture. If the adhesive layer is thinned out, the adhesive may not adhere to the sub-layers resulting in less than ideal bond thickness.
A pressure sensitive adhesive can also be used. For example, laminates, which are fabricated with a layer of adhesive on one or both sides, can be stacked together and bonded under heat and pressure. However, structures with only a few laminate sub-layers can collapse when pressure and heat are applied since they are quite flexible and difficult to work with. For smaller structures, the material must be patterned out by mechanical means or by laser machining. In any case, the problem remains that the adhesives are too thick and will often collapse into the channels resulting in clogging.
The ideal solution would provide clean, sharp edges along the channel walls with no clogging. Accordingly, a need exists for an improved method of fabricating a fluid, gas and/or vacuum flow system that eliminates debris in the fluid flow channels of the manifold and the requirement of cleaning the manifold sub-assembly after manufacture. A method of fabricating a general-purpose flow system, which can receive and transmit either a fluid or gas, would be useful in numerous applications. A fluid, gas and/or vacuum flow system that is cost effective to fabricate, but maintains ideal bond thickness, even for structures with a few sub-layers, would provide numerous advantages.
The present invention provides a method for the fabrication of a bi-directional fluid, gas and/or vacuum flow system. The system includes a laminate gasket manifold containing a plurality of bi-directional fluid-flow channels. With the present invention, a four-color ink jet print head, for example, that consists of one monolithic silicon die with one or more arrays of nozzles for each color can be fabricated.
Disclosed in one embodiment is a method for the fabrication of a fluid, gas and/or vacuum flow system having a laminate gasket manifold containing a plurality of bi-directional fluid-flow channels therein. The method comprises the step of applying a bonding material, such as a photoimagable polyimide dry film resist, to one or more stiffening elements in order to form laminate sub-layers. The application of the photoimagable polyimide dry film resist is performed on one or both sides of the stiffening elements, such as stainless steel, Invar or copper. As such, an image developed on both sides of each laminate sub-layer during registration is created.
The method also comprises the step of patterning the resist to form a plurality of openings therein. Openings in the dry film are patterned on both sides of the laminate sub-layers using a pre-registered or pre-aligned photomask. The pattern is then defined by removing the photoresist from the selected pattern area. As such, the stainless steel is etched from the laminate sub-layers to form alignment apertures therein. Thus, etching is performed separately on the laminate sub-layers utilizing an array format. Once the alignment apertures are formed, pins are set in the alignment apertures using a flex-mass board designed to keep the laminate sub-layers aligned.
The method further comprises the step of stacking the resist-coated sub-layers such that the alignment apertures therein are aligned to each other, respectively, to form bi-directional fluid, gas, and/or vacuum channels. Heat and pressure is then applied to the stack whereby the laminate sub-layers are bonded together to form a laminate gasket manifold. In one embodiment, the laminate gasket manifold is heated at 70 to 75 degrees C. in a vacuum laminator for 10 to 30 seconds in order to tack the laminate sub-layers together. This process results in the bonding material, or photoimagable polyimide dry film resist layers, of the laminate gasket manifold not reaching a fully cross-linked state. The laminate gasket manifold can then be placed between additional parts, such as a substrate providing fluid, gas and/or vacuum inlets, and a structure, such as an ink jet silicon aperture structure.
Together, the laminate gasket manifold and additional parts are bonded to form a fluid, gas and/or vacuum flow system. The laminate gasket manifold is first aligned with the fluid, gas and/or vacuum inlets and outlets in the substrate. The substrate may include a mounting block comprising a metal such as stainless steel, a ceramic such as zirconium oxide, or a glass such as Pyrex or quartz. The laminate gasket manifold is then aligned with the nozzles, or orifices of the silicon aperture structure. As such, a precision die bonder can be used to accurately align the structures. In using the die bonder, pressure is applied to the gasket manifold and heated at 160 degrees C. The gasket manifold is held at this temperature and pressure for approximately five minutes in order to adhere the substrate to one side of the laminate gasket manifold and the silicon aperture structure to the other side.
To fully cross-link the bonding material, a post bake, or curing process, at 160 degrees C. for one hour is used with a static pressure, such as a dead weight, that presses the flow system together during the cross-linking process. However, if the laminate gasket manifold is not to be used to bond other parts together, heating the laminate sub-assembly via a post bake under pressure at 160 degrees C. for one hour will fully cross-link the bonding material.
According to another embodiment, disclosed is a fluid, gas and/or vacuum flow system comprising a laminate gasket manifold containing a plurality of bi-directional fluid-flow channels therein. The laminate gasket manifold further comprises one or more laminate sub-layers. The laminate sub-layers each, in turn, comprise one layer including a stiffening element and one or two layers of bonding material, such as a polyimide dry film resist, which resists dissolution upon contact with the fluid. The stiffening elements are chosen from the group consisting of: stainless steel, Invar or copper. The number of laminate sub-layers is proportional to the number of different fluid-flow channel exit applications. As such, all laminate sub-layers are stacked in an aligned manner to register the alignment apertures to each another and placed in a position for bonding together.
The flow system also comprises a silicon aperture structure which forms a top layer over the laminate gasket manifold. The silicon aperture structure further includes a plurality of alignment apertures designed to constrain the fluid flow via the channels.
The flow system further comprises a means for receiving and transmitting fluid through the flow channels of the laminate gasket manifold and exit the alignment apertures of the silicon aperture structure. The means for receiving and transmitting fluid through the channels of the laminate gasket manifold is housed in a substrate, or mounting block. The mounting block comprises a metal such as stainless steel, a ceramic such as zirconium oxide, or a glass such as Pyrex or quartz. Furthermore, the means for receiving and transmitting fluid can be utilized as a vacuum for cleaning where debris or other fluids may be found.
In one specific application, the flow system discussed is utilized with an ink jet print head. Further disclosed is a fluid-flow apparatus for use with ink jet systems and similar devices comprising a laminate gasket manifold containing a plurality of bi-directional fluid-flow channels therein. The laminate gasket manifold further includes a polyimide dry film resist, which resists dissolution upon contact with ink. The laminate gasket manifold also comprises one or more laminate sub-layers etched to form the fluid-flow channels. Each laminate sub-layer comprises one layer, including a stiffening element, and one or two layers of polyimide dry film. The polyimide dry film resist is applied to one or both sides of the stiffening elements so as to form a laminate sub-layer. The stiffening elements are chosen from the group consisting of: stainless steel, Invar or copper. The laminate sub-layers are then stacked in an aligned manner to register the alignment apertures to each other for bonding and to form fluid-flow channel exit applications therein. As such, the number of sub-layers is proportional to the number of different fluid-flow channel exit applications.
The apparatus also comprises a silicon aperture structure forming a top layer over the laminate gasket manifold. The silicon aperture structure is further adapted to connect to an ink jet system for flow of ink.
The apparatus further comprises a means for feeding ink through the channels of the laminate gasket manifold and exit the alignment apertures of the silicon aperture structure. The means for feeding ink through the channels of the gasket manifold is housed in a mounting block, which comprises a metal such as stainless steel, a ceramic such as zirconium oxide, or a glass such as Pyrex or quartz. Thus, the mounting block is attached to an ink reservoir for flow through the laminate gasket manifold.
Technical advantages of the present invention include photofabrication of the manifold which leaves no particulate debris, such as with laser machining, ultrasonic drilling, and other prior art fabrication techniques. Since debris and adhesive spills into the channels are eliminated, no cleaning of the manifold sub-assembly is required.
Other technical advantages include the use of polyimide which is a compliant material and which permits bonding material together with different thermal expansions, such as stainless steel and silicon. Thus, the stiffening material can be selected to closely match the silicon, with regard to its thermal expansion. That is, Invar, that has a thermal expansion which closely resembles that of silicon, can be used instead of the stainless steel. The thickness of these materials can be adjusted to minimize the stress induced in the silicon from the bonding operation. Still another advantage is that the thickness of the stiffening material can be adjusted to provide a given flexibility necessary for other applications.